{
    "lazyNodes": false,
    "abFitnotesFlag": false,
    "abCrawlReviews": false,
    "productOptionsCookie": false,
    "orderDelayFlag": false,
    "skipSessionCookie": false,
    "covidMessage": false,
    "fullTitleCookie": false,
    "nrLoggerCookie": false,
    "checkoutReviewCookie": false,
    "productOptionSeqCookie": false,
    "maintenanceFlag": false,
    "bufferETACookie": false,
    "multiShippingDiscountFlag": false,
    "newFitmentFlag": false,
    "surveyOptInFlag": false,
    "crossSellFlag": false,
    "skuMappingFlag": false,
    "paySplitCookie": false,
    "callDisableFlag": false,
    "zipPaymentFlag": "u",
    "hassleFreeReturn": false,
    "lifetimeReplacement": false,
    "cpn_off": false
}
2001 Ford F-150
1
0
Price Match Guarantee
60-Day Returns
Lifetime Replacement
Price Match Guarantee
60-Day Returns
Lifetime Replacement
2001 Ford F-150

2001 Ford F-150 Accessory Belt Idler Pulleys

Refine by:

Shop Catalog

Showing 1 - 15 of 38 results
Display item:
15
30
45
Sort by:
Accessory Belt Idler Pulley, 8 Cyl 5.4L, With A.C. - Main Drive -
Replacement
Accessory Belt Idler Pulley, 8 Cyl 5.4L, With A.C. - Main Drive -
Part Number: REPF317403
Guaranteed to Fit
$8.22
Vehicle Fitment
  • 2001 Ford F-150 XL 8 Cyl 4.6L With A.C.
  • 2001 Ford F-150 Harley-Davidson Edition 8 Cyl 5.4L With A.C.
  • 2001 Ford F-150 King Ranch 8 Cyl 4.6L With A.C.
  • 2001 Ford F-150 XL 8 Cyl 5.4L With A.C.
  • 2001 Ford F-150 XLT 8 Cyl 4.6L With A.C.
  • 2001 Ford F-150 Lariat 8 Cyl 5.4L With A.C.
  • 2001 Ford F-150 Lightning 8 Cyl 5.4L With A.C.
  • 2001 Ford F-150 XLT 8 Cyl 5.4L With A.C.
  • 2001 Ford F-150 Lariat 8 Cyl 4.6L With A.C.
  • 2001 Ford F-150 King Ranch 8 Cyl 5.4L With A.C.
Product Details
Notes : Steel; Serpentine; Flat; 0.67 in. inside diameter; 2.99 in. outside diameter; 1.46 in. widthWarranty : 1-year Replacement unlimited-mileage warrantyQuantity Sold : Sold individuallyProp 65 Warning :

Warning SymbolWARNING: This product can expose you to chemicals including Lead, which is known to the State of California to cause cancer and birth defects or other reproductive harm. For more information go to www.P65Warnings.ca.gov.

Numberof Grooveson Pulley : 0Interchange Part Number : 89016, 38023, 49017, 231016, 419612, 2W9319A216BA, 31170R40A02, C2C22758, PQG500130, RE518988Replaces OE Number : 38023, 49017, 231016, 419612, 2W9319A216BA, 31170R40A02, C2C22758, PQG500130, RE518988Recommended Use : OE ReplacementProduct Fit : Direct FitReturns Policy : 30-Day Return Policy
Accessory Belt Idler Pulley, 6 Cyl 4.2L, Truck -
AC Delco®
Accessory Belt Idler Pulley, 6 Cyl 4.2L, Truck -
Part Number: AC38009
Guaranteed to Fit
$18.99
Vehicle Fitment
  • 2001 Ford F-150 XLT 6 Cyl 4.2L Truck
  • 2001 Ford F-150 XL 6 Cyl 4.2L Truck
Product Details
Notes : With dual sided V-ribbed belt and grooved pulleyWarranty : 24-months or unlimited mile AC Delco limited warrantyQuantity Sold : Sold individuallyProp 65 Warning :

Warning SymbolWARNING: This product can expose you to chemical which is known to the State of California to cause cancer and birth defects or other reproductive harm. For more information go to www.P65Warnings.ca.gov.

Series : Professional SeriesNumberof Grooveson Pulley : 6Replaces OE Number : 88909590Recommended Use : OE ReplacementProduct Fit : Direct Fit
Accessory Belt Idler Pulley, 8 Cyl 5.4L, Smooth Pulley -
Dorman®
Accessory Belt Idler Pulley, 8 Cyl 5.4L, Smooth Pulley -
Part Number: RB419605
Guaranteed to Fit
$24.99
Vehicle Fitment
  • 2001 Ford F-150 XL 8 Cyl 4.6L Smooth Pulley
  • 2001 Ford F-150 Harley-Davidson Edition 8 Cyl 5.4L Smooth Pulley
  • 2001 Ford F-150 King Ranch 8 Cyl 4.6L Smooth Pulley
  • 2001 Ford F-150 XL 8 Cyl 5.4L Smooth Pulley
  • 2001 Ford F-150 XLT 8 Cyl 4.6L Smooth Pulley
  • 2001 Ford F-150 Lariat 8 Cyl 5.4L Smooth Pulley
  • 2001 Ford F-150 Lightning 8 Cyl 5.4L Smooth Pulley
  • 2001 Ford F-150 XLT 8 Cyl 5.4L Smooth Pulley
  • 2001 Ford F-150 Lariat 8 Cyl 4.6L Smooth Pulley
  • 2001 Ford F-150 King Ranch 8 Cyl 5.4L Smooth Pulley
Product Details
Warranty : Lifetime Dorman limited warrantyQuantity Sold : Sold individuallyProp 65 Warning :

Warning SymbolWARNING: This product can expose you to chemical which is known to the State of California to cause cancer and birth defects or other reproductive harm. For more information go to www.P65Warnings.ca.gov.

Series : Techoice SeriesInterchange Part Number : REPF317402, 45014, 5014, YS238, 45900, 38022, 5900, 89048, 1844541C1, E7TZ6B209H, F4TZ6B209AA, F5PZ6B209A, F5TZ6B209AA, F5TZ8678C, F5TZ8678E, F5ZZ3A732AA, F65Z8678AA, F65Z8678AAA, F6TZ8678GB, F7TZ6B209AA, F8TE19A216FA, F8TZ8678FA, YC3Z8678AB, 49008, 49139, 50010Replaces OE Number : YS238, 45900, 38022, 5900, 89048, 1844541C1, E7TZ6B209H, F4TZ6B209AA, F5PZ6B209A, F5TZ6B209AA, F5TZ8678C, F5TZ8678E, F5ZZ3A732AA, F65Z8678AA, F65Z8678AAA, F6TZ8678GB, F7TZ6B209AA, F8TE19A216FA, F8TZ8678FA, YC3Z8678AB, 49008, 49139, 50010Product Fit : Direct Fit
Accessory Belt Idler Pulley, 8 Cyl 4.6L -
Motorcraft®
Accessory Belt Idler Pulley, 8 Cyl 4.6L -
Part Number: MIYS250
Guaranteed to Fit
$37.49
Vehicle Fitment
  • 2001 Ford F-150 Lariat 8 Cyl 5.4L
  • 2001 Ford F-150 XL 8 Cyl 4.6L
  • 2001 Ford F-150 Harley-Davidson Edition 8 Cyl 5.4L
  • 2001 Ford F-150 King Ranch 8 Cyl 4.6L
  • 2001 Ford F-150 Lightning 8 Cyl 5.4L
  • 2001 Ford F-150 XL 8 Cyl 5.4L
  • 2001 Ford F-150 XLT 8 Cyl 5.4L
  • 2001 Ford F-150 Lariat 8 Cyl 4.6L
  • 2001 Ford F-150 King Ranch 8 Cyl 5.4L
  • 2001 Ford F-150 XLT 8 Cyl 4.6L
Product Details
Notes : Steel; 17 mm Inside Diameter; 90 mm Outside DiameterWarranty : 2-year or unlimited-mile Motorcraft limited warrantyQuantity Sold : Sold individuallyProp 65 Warning :

Warning SymbolWARNING: This product can expose you to chemical which is known to the State of California to cause cancer and birth defects or other reproductive harm. For more information go to www.P65Warnings.ca.gov.

Series : Motorcraft OE ReplacementProduct Fit : Direct Fit
Accessory Belt Idler Pulley No Slack Series
Dayco®
Accessory Belt Idler Pulley No Slack Series
Part Number: DY89051
Guaranteed to Fit
$18.99
Vehicle Fitment
  • 2001 Ford F-150 XLT 6 Cyl 4.2L
  • 2001 Ford F-150 XL 6 Cyl 4.2L
Product Details
Location : Grooved PulleyWarranty : Dayco limited warrantyQuantity Sold : Sold individuallyProp 65 Warning :

Warning SymbolWARNING: This product can expose you to chemical which is known to the State of California to cause cancer and birth defects or other reproductive harm. For more information go to www.P65Warnings.ca.gov.

Series : No Slack SeriesNumberof Grooveson Pulley : 6Interchange Part Number : REPC313813Product Fit : Direct Fit
Accessory Belt Idler Pulley, 8 Cyl 5.4L - - Supercharger
Dayco®
Accessory Belt Idler Pulley, 8 Cyl 5.4L - - Supercharger
Part Number: DY89048
Guaranteed to Fit
$25.99
Vehicle Fitment
  • 2001 Ford F-150 Harley-Davidson Edition 8 Cyl 5.4L
  • 2001 Ford F-150 King Ranch 8 Cyl 4.6L
  • 2001 Ford F-150 XLT 8 Cyl 4.6L
  • 2001 Ford F-150 Lightning 8 Cyl 5.4L
  • 2001 Ford F-150 XL 8 Cyl 4.6L
  • 2001 Ford F-150 XL 8 Cyl 5.4L
  • 2001 Ford F-150 Lariat 8 Cyl 5.4L
  • 2001 Ford F-150 XLT 8 Cyl 5.4L
  • 2001 Ford F-150 Lariat 8 Cyl 4.6L
  • 2001 Ford F-150 King Ranch 8 Cyl 5.4L
Product Details
Location : SuperchargerWarranty : Dayco limited warrantyQuantity Sold : Sold individuallyProp 65 Warning :

Warning SymbolWARNING: This product can expose you to chemical which is known to the State of California to cause cancer and birth defects or other reproductive harm. For more information go to www.P65Warnings.ca.gov.

Series : No Slack SeriesInterchange Part Number : REPF317402, 45014, 5014Product Fit : Direct Fit
Accessory Belt Idler Pulley HD Solutions Series
Dorman®
Accessory Belt Idler Pulley HD Solutions Series
Part Number: RB4195001
Guaranteed to Fit
$16.99
Vehicle Fitment
  • 2001 Ford F-150 XLT 6 Cyl 4.2L Grooved Pulley
  • 2001 Ford F-150 XL 6 Cyl 4.2L Grooved Pulley
Product Details
Notes : 20 mm Max Belt Width; 17 mm Pulley Bearing Inside Diameter; 12 mm Pulley Bearing Width; 82 mm Pulley Diameter; Serpentine TypeWarranty : 3-year or unlimited-mile Dorman limited warrantyQuantity Sold : Sold individuallyProp 65 Warning :

Warning SymbolWARNING: This product can expose you to chemical which is known to the State of California to cause cancer and birth defects or other reproductive harm. For more information go to www.P65Warnings.ca.gov.

Series : HD Solutions SeriesNumberof Grooveson Pulley : 6-Groove PulleyInterchange Part Number : 38009, 15-4956, 15-4974, 89009, 4792259AC, 4792259AD, 53013926AA, 53031045, 10044867, 10069954, 10115875, 10186174, 10186197, 12552360, 12554701, 12563083, 12564509, 12580162, 12580828, 12581701, 12603527, 12611936, 24502736, 24502989, 90528760, 9157962, 9202550, E8DZ6B209A, E8TZ8678C, E8ZZ8678A, E9SZ6B209D, F4DZ6B209A, F4SZ6B209B, F65Z6B209MA, F68Z6B209AA, 31190R0A005, 8100999840, 816.49003, 49003Replaces OE Number : 38009, 15-4956, 15-4974, 89009, 4792259AC, 4792259AD, 53013926AA, 53031045, 10044867, 10069954, 10115875, 10186174, 10186197, 12552360, 12554701, 12563083, 12564509, 12580162, 12580828, 12581701, 12603527, 12611936, 24502736, 24502989, 90528760, 9157962, 9202550, E8DZ6B209A, E8TZ8678C, E8ZZ8678A, E9SZ6B209D, F4DZ6B209A, F4SZ6B209B, F65Z6B209MA, F68Z6B209AA, 31190R0A005, 8100999840, 816.49003, 49003Material : Polyamide With Glass Fiber FillRecommended Use : OE ReplacementProduct Fit : Direct Fit
Accessory Belt Idler Pulley, 8 Cyl 5.4L, With A.C. - Main Drive -
Dayco®
Accessory Belt Idler Pulley, 8 Cyl 5.4L, With A.C. - Main Drive -
Part Number: DY89016
Guaranteed to Fit
$20.49
Vehicle Fitment
  • 2001 Ford F-150 XL 8 Cyl 4.6L With A.C.
  • 2001 Ford F-150 Harley-Davidson Edition 8 Cyl 5.4L With A.C.
  • 2001 Ford F-150 King Ranch 8 Cyl 4.6L With A.C.
  • 2001 Ford F-150 XL 8 Cyl 5.4L With A.C.
  • 2001 Ford F-150 XLT 8 Cyl 4.6L With A.C.
  • 2001 Ford F-150 Lariat 8 Cyl 5.4L With A.C.
  • 2001 Ford F-150 Lightning 8 Cyl 5.4L With A.C.
  • 2001 Ford F-150 XLT 8 Cyl 5.4L With A.C.
  • 2001 Ford F-150 Lariat 8 Cyl 4.6L With A.C.
  • 2001 Ford F-150 King Ranch 8 Cyl 5.4L With A.C.
Product Details
Warranty : Dayco limited warrantyQuantity Sold : Sold individuallyProp 65 Warning :

Warning SymbolWARNING: This product can expose you to chemical which is known to the State of California to cause cancer and birth defects or other reproductive harm. For more information go to www.P65Warnings.ca.gov.

Series : No Slack SeriesInterchange Part Number : REPF317403, 38023, 49017, 231016, 419612, 2W9319A216BA, 31170R40A02, C2C22758, PQG500130, RE518988Replaces OE Number : 38023, 49017, 231016, 419612, 2W9319A216BA, 31170R40A02, C2C22758, PQG500130, RE518988Product Fit : Direct Fit
Accessory Belt Idler Pulley, 6 Cyl 4.2L, Truck -
AC Delco®
Accessory Belt Idler Pulley, 6 Cyl 4.2L, Truck -
Part Number: AC38007
Guaranteed to Fit
$20.49
Vehicle Fitment
  • 2001 Ford F-150 XL 6 Cyl 4.2L Truck
  • 2001 Ford F-150 XLT 6 Cyl 4.2L Truck
Product Details
Notes : With smooth pulleyWarranty : 24-months or unlimited mile AC Delco limited warrantyQuantity Sold : Sold individuallyProp 65 Warning :

Warning SymbolWARNING: This product can expose you to chemical which is known to the State of California to cause cancer and birth defects or other reproductive harm. For more information go to www.P65Warnings.ca.gov.

Series : Professional SeriesReplaces OE Number : 88909588Recommended Use : OE ReplacementProduct Fit : Direct Fit
Accessory Belt Idler Pulley, 6 Cyl 4.2L, Accessory Drive; Smooth Pulley -
ContiTech®
Accessory Belt Idler Pulley, 6 Cyl 4.2L, Accessory Drive; Smooth Pulley -
Part Number: CTT49007
Guaranteed to Fit
$18.49
Vehicle Fitment
  • 2001 Ford F-150 XL 6 Cyl 4.2L Accessory Drive; Smooth Pulley
  • 2001 Ford F-150 XLT 6 Cyl 4.2L Accessory Drive; Smooth Pulley
Product Details
Warranty : 5-year ContiTech limited warrantyQuantity Sold : Sold individuallyProp 65 Warning :

Warning SymbolWARNING: This product can expose you to chemical which is known to the State of California to cause cancer and birth defects or other reproductive harm. For more information go to www.P65Warnings.ca.gov.

Material : ThermoplasticRecommended Use : OE ReplacementProduct Fit : Direct Fit
Accessory Belt Idler Pulley, 8 Cyl 4.6L, Without Air Conditioning -
Gates®
Accessory Belt Idler Pulley, 8 Cyl 4.6L, Without Air Conditioning -
Part Number: GAT38053
Guaranteed to Fit
$22.99
Vehicle Fitment
  • 2001 Ford F-150 Lariat 8 Cyl 5.4L Without Air Conditioning
  • 2001 Ford F-150 XL 8 Cyl 4.6L Without Air Conditioning
  • 2001 Ford F-150 Harley-Davidson Edition 8 Cyl 5.4L Without Air Conditioning
  • 2001 Ford F-150 King Ranch 8 Cyl 4.6L Without Air Conditioning
  • 2001 Ford F-150 Lightning 8 Cyl 5.4L Without Air Conditioning
  • 2001 Ford F-150 XL 8 Cyl 5.4L Without Air Conditioning
  • 2001 Ford F-150 XLT 8 Cyl 5.4L Without Air Conditioning
  • 2001 Ford F-150 Lariat 8 Cyl 4.6L Without Air Conditioning
  • 2001 Ford F-150 King Ranch 8 Cyl 5.4L Without Air Conditioning
  • 2001 Ford F-150 XLT 8 Cyl 4.6L Without Air Conditioning
Product Details
Quantity Sold : Sold individuallyProp 65 Warning :

Warning SymbolWARNING: This product can expose you to chemical which is known to the State of California to cause cancer and birth defects or other reproductive harm. For more information go to www.P65Warnings.ca.gov.

Numberof Grooveson Pulley : 8Product Fit : Direct Fit
Accessory Belt Idler Pulley, 8 Cyl 5.4L, Without AC -
4-Seasons®
Accessory Belt Idler Pulley, 8 Cyl 5.4L, Without AC -
Part Number: FS45045
Guaranteed to Fit
$28.99
Vehicle Fitment
  • 2001 Ford F-150 XL 8 Cyl 4.6L Without AC
  • 2001 Ford F-150 Harley-Davidson Edition 8 Cyl 5.4L Without AC
  • 2001 Ford F-150 King Ranch 8 Cyl 4.6L Without AC
  • 2001 Ford F-150 XL 8 Cyl 5.4L Without AC
  • 2001 Ford F-150 XLT 8 Cyl 4.6L Without AC
  • 2001 Ford F-150 Lariat 8 Cyl 5.4L Without AC
  • 2001 Ford F-150 Lightning 8 Cyl 5.4L Without AC
  • 2001 Ford F-150 XLT 8 Cyl 5.4L Without AC
  • 2001 Ford F-150 Lariat 8 Cyl 4.6L Without AC
  • 2001 Ford F-150 King Ranch 8 Cyl 5.4L Without AC
Product Details
Warranty : 1 year or 12,000-mile 4-Seasons limited warrantyQuantity Sold : Sold individuallyProp 65 Warning :

Warning SymbolWARNING: This product can expose you to chemical which is known to the State of California to cause cancer and birth defects or other reproductive harm. For more information go to www.P65Warnings.ca.gov.

Material : SteelRecommended Use : OE ReplacementProduct Fit : Direct Fit
Accessory Belt Idler Pulley, 8 Cyl 4.6L, Truck, With Air Conditioning -
AC Delco®
Accessory Belt Idler Pulley, 8 Cyl 4.6L, Truck, With Air Conditioning -
Part Number: AC38023
Guaranteed to Fit
$23.49
Vehicle Fitment
  • 2001 Ford F-150 Lariat 8 Cyl 5.4L Truck, With Air Conditioning
  • 2001 Ford F-150 XL 8 Cyl 4.6L Truck, With Air Conditioning
  • 2001 Ford F-150 Harley-Davidson Edition 8 Cyl 5.4L Truck, With Air Conditioning
  • 2001 Ford F-150 King Ranch 8 Cyl 4.6L Truck, With Air Conditioning
  • 2001 Ford F-150 Lightning 8 Cyl 5.4L Truck, With Air Conditioning
  • 2001 Ford F-150 XL 8 Cyl 5.4L Truck, With Air Conditioning
  • 2001 Ford F-150 XLT 8 Cyl 5.4L Truck, With Air Conditioning
  • 2001 Ford F-150 Lariat 8 Cyl 4.6L Truck, With Air Conditioning
  • 2001 Ford F-150 King Ranch 8 Cyl 5.4L Truck, With Air Conditioning
  • 2001 Ford F-150 XLT 8 Cyl 4.6L Truck, With Air Conditioning
Product Details
Notes : With smooth pulleyWarranty : 24-months or unlimited mile AC Delco limited warrantyQuantity Sold : Sold individuallyProp 65 Warning :

Warning SymbolWARNING: This product can expose you to chemical which is known to the State of California to cause cancer and birth defects or other reproductive harm. For more information go to www.P65Warnings.ca.gov.

Series : OE Replacement SeriesRecommended Use : OE ReplacementProduct Fit : Direct Fit
Accessory Belt Idler Pulley, 6 Cyl 4.2L - Grooved Pulley
Gates®
Accessory Belt Idler Pulley, 6 Cyl 4.2L - Grooved Pulley
Part Number: GAT36327
Guaranteed to Fit
$24.99
Vehicle Fitment
  • 2001 Ford F-150 XL 6 Cyl 4.2L
  • 2001 Ford F-150 XLT 6 Cyl 4.2L
Product Details
Location : Grooved PulleyWarranty : Lifetime Gates limited warrantyQuantity Sold : Sold individuallyProp 65 Warning :

Warning SymbolWARNING: This product can expose you to chemical which is known to the State of California to cause cancer and birth defects or other reproductive harm. For more information go to www.P65Warnings.ca.gov.

Product Fit : Direct Fit
Accessory Belt Idler Pulley Techoice Series
Dorman®
Accessory Belt Idler Pulley Techoice Series
Part Number: RB419631
Guaranteed to Fit
$27.49
Vehicle Fitment
  • 2001 Ford F-150 XL 6 Cyl 4.2L Grooved Pulley; Without Air Conditioning
  • 2001 Ford F-150 XLT 6 Cyl 4.2L Grooved Pulley; Without Air Conditioning
Product Details
Location : Upper Or LowerNotes : (1) Mount Hole Quantity; 20 mm Maximum Belt Width; 17 mm Pulley Bearing Inside Diameter; 12 mm Pulley Bearing Width; 70 mm Pulley Diameter; 28.5 mm Pulley Width; Black Color; Serpentine Pulley TypeWarranty : Lifetime Dorman limited warrantyQuantity Sold : Sold individuallyProp 65 Warning :

Warning SymbolWARNING: This product can expose you to chemical which is known to the State of California to cause cancer and birth defects or other reproductive harm. For more information go to www.P65Warnings.ca.gov.

Series : Techoice SeriesInterchange Part Number : YS315, 45066, 45976, 36327, 36818, 38019, 5066, 5976, 14103118, 89012, 53002903, 4W4E6C348AA, 4W4Z6C348AA, 5L3E19A216AA, 5L3Z8678AA, F75Z8678BA, F75Z8678BB, AJ89037, SK89004, SK89012, SK89048, 49001, 49016, 50003Replaces OE Number : YS315, 45066, 45976, 36327, 36818, 38019, 5066, 5976, 14103118, 89012, 53002903, 4W4E6C348AA, 4W4Z6C348AA, 5L3E19A216AA, 5L3Z8678AA, F75Z8678BA, F75Z8678BB, AJ89037, SK89004, SK89012, SK89048, 49001, 49016, 50003Material : SteelRecommended Use : OE ReplacementProduct Fit : Direct Fit
Page 1 of 3 | Showing 1 - 15 of 38 results

Top Rated Products

Replacement Accessory Belt Idler Pulley, 8 Cyl 4.6L, With A.C. - Main Drive -
$9.49( Review)
Pulley was just as described. The part appears to be OEM quality and installed withouSee More
Jeffrey T.
VERIFIED PURCHASER
Dorman Accessory Belt Idler Pulley HD Solutions Series
$16.99( Review)
Sold part, fits and works as intended.
Philip H.
VERIFIED PURCHASER

Popular Products

Helpful Automotive Resources

Where is the Idler Pulley Located?
Where is the Idler Pulley Located?Accessing the idler pulley can be deceptively tricky and you’ll need tools like a socket set and a torque wrench. It varies though, and on some engines it’s very easy but the belt needs to be removed first. .ub4e76001c794232f21c1de76b2d13918 { padding:0px; margin: 0; padding-top:1em!important; padding-bottom:1em!important; width:100%; display: block; font-weight:bold; background-color:#eaeaea;
Bad Idler Pulley Symptoms Plus Replacement Recommendations
Bad Idler Pulley Symptoms Plus Replacement RecommendationsTo fully understand the function of an idler pulley, let’s look at how the whole mechanism works. If you own a modern vehicle, it probably has one serpentine belt rather than multiple V-belts.